EP0700210B1

EP0700210B1 - Television set speaker system

Info

Publication number: EP0700210B1
Application number: EP95305998A
Authority: EP
Inventors: Hitsohi 433-10 Ohaza Kamihara Saito; Hitoshi Sango
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 1994-08-30
Filing date: 1995-08-29
Publication date: 1999-12-22
Anticipated expiration: 2015-08-29
Also published as: EP0700210A3; EP0700210A2; JP3449571B2; DE700210T1; CN1054254C; KR100231094B1; KR960009689A; DE69514055T2; DE69514055D1; TW428870U; HK1014231A1; CN1125378A; US5710394A; JPH0879659A

Description

Background of the Invention

Field of the Invention:

This invention relates to television set speaker systems and more particularly to a television set speaker system intended to expand a audio reproducing frequency band and to reproduce a stereo audio sound accurately.

Description of the Related Art:

Generally, in a television set, a speaker arranging place is mostly occupied by a cathode ray tube setting place and therefore the speaker is arranged on both sides or the upper or lower part of the cathode ray tube.
Recently, as the picture screen is made larger and wider, the appearance design of the television set tends to become slimmer and the form of the speaker reproducing sounds can not help becoming thinner.
However, in a speaker in which the horizontal width of the diaphragm is made smaller, due to the diaphragm area and the diaphragm system supporting means, the low frequency reproducing capacity will be hard to obtain. Therefore, an acoustic waveguide (also called a horn for speaker) arranged on the front surface of a speaker so as to guide sound waves emitting from the speaker diaphragm to a sound radiating mouth has been already variously developed as a means of slimming the television set.
However, in such television set speaker system, it is usual to convert a sound pressure level within the acoustic waveguide and at the mouth in order to improve the performance of the sounds radiated from the mouth of the acoustic waveguide, therefore the area of the sound radiating mouth will become smaller than the diaphragm area of the speaker to be used, the sound pressure level radiated from the mouth will reduce and the sound volume feeling and "live" feeling will be lacking in the present situation.
A conventional television set speaker system is shown in Figs. 5 and 6.
In Fig. 5, the reference numeral 10 represents a television set. Within a television set cabinet 11, left and right channel speakers 13 and 14 are arranged respectively in the left and right positions on both sides of a cathode ray tube 12. Acoustic waveguides 15 and 16 are fitted respectively to the front surface parts of the left and right channel speakers 13 and 14 and the sound radiating mouths 17 and 18 respectively of the left and right acoustic waveguides 15 and 16 are arranged near the front panel (front surface frame) of the television cabinet 11.
In the formation in Fig. 5, as no back cabinet is arranged in the rear of the speakers 13 and 14, the sounds radiated from the rear diaphragm of the speaker will be radiated around from ventilating holes 19 and 20 provided around the television set cabinet 11. At this time, the areas of the sound radiating mouths 17 and 18 are so smaller than the diaphragm areas of the speakers 13 and 14 as mentioned above that, when the sound pressure levels radiated from the sound radiating mouths 17 and 18 have been reduced, the sound pressure level radiated from the speaker rear surface part will become larger, the sounds radiated around from the ventilating holes 19 and 20 will mask the sounds on the front side from the mouths 17 and 18, the sound quality will become unclear and the left and right stereo separations will deteriorate. There are such defects.
Therefore, in case the sound quality is considered to be important, as in the formation in Fig. 6, back cabinets (sealed boxes) 21 and 22 will be often arranged in the rear of the left and right channel speakers 13 and 14 respectively with the acoustic waveguides 15 and 16 arranged in the front surface parts.
However, in the conventional example in Fig. 6, as the back cabinets 21 and 22 are formed in the limited space of the television set cabinet 11, the back cabinets 21 and 22 will not be able to be formed to a large volume. Therefore, there has been a defect that the low frequency reproducing range will be limited by the volume limitation of the back cabinets 21 and 22. There have been also defects that the sounds emitted from the rear surface parts of the speakers 13 and 14 will be enclosed with the back cabinets 21 and 22 so as not to be radiated out, the sounds radiated out will be only from the sound radiating mouths 17 and 18 and the reproduced sound pressure level will be low.
As mentioned above, there have been already problems that the sounds radiated from the front surface of a television set will be unclear and, in the system in which the back cabinets are arranged in the rear of the speakers, the back cabinets of a large volume will not be able to be formed, therefore the low frequency reproducing range will be limited, the speaker rear part will be sealed and the reproduced sound pressure level will be low.
EP - A 0462571 describes a speaker horn arrangement comprising a cabinet in which front and back horns are provided. A speaker is mounted at the rear part of the front horn. A lid is provided which tightly closes the rear part of the speaker and a bass-reflex port is formed in the lid.

Summary of the Invention

An object of the present invention is to provide a speaker system for a television set, in which the sounds radiated from the front and rear surfaces of the speaker will not interfere with each other and a sound quality high in the clearness will be obtained.
Another object of the present invention is to provide a speaker system for a television set, in which the sound reproducing range is wide and sounds high in the presence feeling can be reproduced.
In accordance with the present invention, there is provided a speaker system for a television set, comprising:
a television set cabinet;
a speaker having a diaphragm, said speaker being provided within said cabinet so as to radiate sound from said diaphragm to a front of said television set; and an acoustic waveguide, mounted at a front surface side of said speaker within said cabinet for guiding sound radiated from said diaphragm so as to be radiated from a front surface of said television set;

a directional reflector mounted at a rear side of said speaker within said cabinet for reflecting sound radiated from a rear surface part of said speaker diaphragm in a specific direction, said reflector reflecting sound radiated from a rear surface part of said speaker diaphragm diagonally forward from a side surface part of said television set and also diagonally forward from a top surface part of said television set; and
a radiating port formed in said cabinet for radiating out of said cabinet sound reflected by said directional reflector.

In the speaker system of the present invention, while the acoustic waveguide is arranged in the front surface part of the speaker diaphragm so as to radiate the sounds forward, the directional reflector is arranged in the rear surface part of the speaker diaphragm so as to forcibly reflect in the specific direction (for example, the side surface part direction) of the television set the sounds radiated from the rear surface diaphragm and to discharge the sounds out of the television set. Thereby, the sounds on the front and rear surfaces of the speaker diaphragm will not interfere with each other and will be able to be positively radiated in front of the television set and in the specific direction different from it.
In a preferred embodiment of the present invention, said directional reflector includes a reflecting plane part arranged as opposed to the rear surface part of said speaker diaphragm so as to reflect the sound radiated from the rear surface of the diaphragm; a side surface shielding part connected to one side of said reflecting plane part so as to shield sound propagating toward one side; a bottom surface shielding part connected to a bottom end of said reflecting plane part so as to shield sound propagating toward the bottom end; opening parts provided on the other side surface and the upper surface as opposed to said side surface shielding part and bottom surface shielding part so as to radiate the sounds reflected by said reflecting plane part.
In the preferred embodiment, in the television set wherein a pair of the first and second speakers are arranged on the left and right, while the first and second acoustic waveguides are arranged respectively in the front surface parts of the first and second speakers, the first and second directional reflectors are provided respectively in the rear surface parts of the first and second speakers so as to forcibly reflect in the specific direction (for example, the side surface part direction) and discharge out of the television set the sounds in the rear surface parts of the first and second speakers, therefore the sounds on the front surface and rear surface of each speaker diaphragm will not interfere with each other, the left and right waves put out of the respective rear surface diaphragms of the first and second speakers will little interfere with each other. Further, the sounds on the speaker rear surface part reflected, for example, in the side surface part direction by the directional reflector and discharged out of the television set will reach the audience by reflecting against the peripheral wall and therefore a sound quality high in the clearness and presence feeling will be obtained.

Brief Description of the Drawings

Fig. 1 is a perspective view showing a television set speaker system embodying the present invention.
Fig. 2 is a perspective view showing a formation modeling the system in Fig. 1.
Fig. 3 is a perspective view showing one speaker system as disassembled.
Fig. 4 is a vertically sectioned view of Fig. 3 as assembled.
Fig. 5 is a perspective view showing a conventional television set speaker system.
Fig. 6 is a perspective view showing a television set speaker system of another conventional example.

Detailed Description of the Preferred Embodiments

The embodiments shall be explained with reference to the drawings.
Fig. 1 is a perspective view showing a television set speaker system embodying the present invention. Fig. 2 is a perspective view showing the arrangement of the left and right channel speakers within the television set cabinet in Fig. 1. The same components as in the conventional example in Fig. 5 shall bear the same reference numerals in the explanation.
In Fig. 1, a television set 10A is provided with a cathode ray tube 12 and left and right channel speakers 13 and 14 within a television set cabinet 11. The left and right channel speakers 13 and 14 are arranged respectively in the left and right positions on both sides of the cathode ray tube 12. Acoustic waveguides 15 and 16 are arranged respectively in the front surface parts of the left and right channel speakers 13 and 14. Sound radiating mouths 17 and 18 respectively at the tips of the acoustic waveguides 15 and 16 are arranged near the front panel of the television cabinet 11. The sounds radiated from the front surface parts of the respective diaphragms of the speakers 13 and 14 are to be radiated to the front surface of the television set cabinet 11 through the acoustic waveguides 15 and 16.
Directional reflectors 23 and 24 are arranged respectively in the rear surface parts of the left and right channel speakers 13 and 14. These respective left and right directional reflectors 23 and 24 will have the sounds radiated from the rear surface parts of the respective diaphragms of the speakers 13 and 14 reflected by the reflecting plates of a shape opened on one side surface and upper surface (of a substantially bent cross-sectioned plane) and will discharge the sounds in a specific direction (diagonally forward on the side surface part side and diagonally forward on the top surface part side of the cabinet in the drawing) different from the front of said television set cabinet from the mouths. The sound waves reflected by the respective left and right directional reflectors 23 and 24 will be discharged out of the cabinet through the radiating ports 30 and 31 formed respectively in the left and right side surface parts of the cabinet 11. By the way, the radiating ports 30 and 31 may be also ventilating holes.
In such formation, the sounds radiated from the diaphragm front surface parts of the left and right channel speakers 13 and 14 will be radiated forward of the television set 10 from the left and right sound radiating mouths 17 and 18 respectively through the left and right acoustic waveguides 15 and 16. At the same time, the sounds radiated from the diaphragm rear surface parts of the left and right channel speakers 13 and 14 will be respectively reflected by the respective reflecting surfaces of the left and right directional reflectors 23 and 24, will be discharged diagonally forward on the side surface part side and diagonally forward on the top surface part side of the television set cabinet 11 and will be forcibly radiated out of the cabinet through the radiating ports 30 and 31 located in the left and right side surface parts of the television set cabinet 11. As the respective reflecting surfaces of the left and right directional reflectors 23 and 24 are directed diagonally forward and diagonally upward of the television set cabinet 11, the sounds radiated from the respective diaphragm rear parts will be reflected by the reflecting surfaces of the respective directional reflectors 23 and 24 and will be discharged diagonally forward and diagonally upward. By the way, part of the sounds radiated from the diaphragm rear surface parts of the speakers 13 and 14 will be reflected by the top surface part inside surface of the cabinet 11 and will be radiated out of the cabinet through the radiating ports 30 and 31. Therefore, as shown as modeled in Fig. 2, the left and right sound waves A and B put out by the respective diaphragm rear surfaces of the left and right channel speakers 13 and 14 will be made definite in the directivity, therefore the left and right sound waves of the respective speaker rear surfaces will little interfere with each other, the left and right sound separation degree, that is, clearness will be improved, the stereo feeling will increase and there will be obtained the effect that, when the sounds radiated from the side surface are reflected against the wall surface of the room, the expanding feeling of the sounds in the left and right directions will increase.
Fig. 3 is a perspective view showing one speaker system (for example, the right channel speaker system) in Fig. 1 as disassembled. Fig. 4 is a vertically sectioned view of Fig. 3 as assembled.
In Fig. 3, in the speaker system, the acoustic waveguide 16 is fitted to the front surface part of the speaker 14 and the directional reflector 24 is fitted to the rear surface part of the speaker 14. The acoustic waveguide 16 is formed of a horn part 16a provided with a sound radiating mouth 18 on the tip side to radiate sound waves, a waveguide part 16b guiding sound waves to the horn side from the speaker front surface as connected to this horn part 16a and a fitting part 16c connected to the rear end of this waveguide part 16b. The front surface frame part of the speaker 14 is fixed to the fitting part 16c by such locking means as screws. Connecting parts 16c1 and 16c2 are provided as projected outward at the rear end of the fitting frame of the fitting part 16c. The connecting parts 24c1 and 24c2 of the directional reflector 24 are to be connected and fixed to the connecting parts 16c1 and 16c2 of this fitting part 16 by means of screws 26 and 27. The connecting parts 24c1 and 24c2 are formed to be flange-shaped on the outer periphery of the directional reflector 24. The directional reflector 24 is formed of a reflecting plane part 24a wherein a reflecting surface is directed diagonally forward (with respect to the front surface of the television set) and diagonally upward to reflect the sounds radiated from the rear surface part of the speaker 14, a side surface shielding part 24b connected to this reflecting plane part 24a so as to shield sound waves propagating to the central side of the television set (that is, to the cathode ray tube side) and a bottom surface shielding part 24c connected to said reflecting plane part 24a so as to shield sound waves propagating to the bottom surface side of the television set.
When the directional reflector 24 is secured to the fitting part 16c of the acoustic waveguide 16 by screws 26 and 27, as shown in the vertically sectioned view in Fig. 4, the acoustic waveguide 16 will be arranged in front of the front diaphragm 14a of the speaker 14 and the directional reflector 24 will be arranged in the rear of the rear diaphragm 14b of the speaker 14. In Fig. 4, the reference numeral 25 represents a sound absorbing material to prevent resonance with a specific frequency. A cotton-like member is used for the sound absorbing material 25.
By the way, the formation of the directional reflector 24 of the right channel speaker is shown in Figs. 3 and 4. However, the directional reflector 23 of the left channel speaker has a shape symmetrical with the directional reflector 24 but is of the same formation as of the directional reflector 24.
As described above, according to the present invention, the television speaker system which is high in an articulation, gives a presence feeling and expansion feeling and is advantageous in the cost can be realized.
By the way, the present invention is not limited to only the above described embodiments and various modifications can be made in a range not deviating from the subject matter of the invention.

Claims

A speaker system for a television set, comprising:

a television set cabinet (11);

a speaker (14) having a diaphragm, said speaker (14) being provided within said cabinet (11) so as to radiate sound from said diaphragm to a front of said television set (10A); and

an acoustic waveguide (16), mounted at a front surface side of said speaker (14) within said cabinet (11) for guiding sound radiated from said diaphragm so as to be radiated from a front surface of said television set (10A);

characterized in that it comprises:

a directional reflector (24) mounted at a rear side of said speaker (14) within said cabinet (11) for reflecting sound radiated from a rear surface part of said speaker diaphragm in a specific direction, said reflector (24) reflecting sound radiated from a rear surface part of said speaker diaphragm diagonally forward from a side surface part of said television set (10A) and also diagonally forward from a top surface part of said television set (10A); and

a radiating port (31) formed in said cabinet (11) for radiating out of said cabinet (11) sound reflected by said directional reflector (24).
A speaker system for a television set according to claim 1, wherein:

said directional reflector is further characterized in that it includes:

a reflecting plane part (24a) arranged as opposed to the rear surface part of said speaker diaphragm so as to reflect the sound radiated from the rear surface of the diaphragm; a side surface shielding part (24b) connected to one side of said reflecting plane part (24a) so as to shield sound propagating toward one side; a bottom surface shielding part (24c) connected to a bottom end of said reflecting plane part (24a) so as to shield sound propagating toward the bottom end; and opening parts provided on the other side surface and the upper surface as opposed to said side surface shielding part (24b) and bottom surface shielding part (24c) so as to radiate the sounds reflected by said reflecting plane part (24a).
A speaker system for a television set according to claims 1 or 2, wherein a pair of said speakers, a pair of said acoustic waveguides and a pair of said directional reflectors are symmetrically provided on the left and on the right respectively within said cabinet (11), and also a pair of said radiating ports are symmetrically provided at the left side and at the right side of said cabinet (11) respectively.